Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          503        190 
1992          936        367 
1993         1669        610 
1994         2326        839 
1995         3735       1294 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14535       5574 
2000        40499      16806 
2001        43092      16711 
2002        32557      14554 
2003        61340      25428 
2004        48063      18435 
2005        85681      26339 
2006       111098      35493 
2007       204758      62770 
2008       125834      35802 
2009       102420      28777 
2010       118957      33029 
2011       178526      49370 
2012       166021      45867 
2013       256960      72803 
2014       643176     163321 
2015       747658     197344 
2016       574589     152978 
2017       611891     163877 
2018       404226     112901 
2019       942887     230868 
2020       692347     177538 
2021       899308     215370 
2022       668042     191087 
2023       607175     174810 
2024       198412      57054